Pressor Activity in Bovine Kidney Homogenate

Abstract

Cadmium and zinc ions added separately to male bovine kidney homogenate increased pressor activity fourfold to fivefold after at least ten hours of incubation. Dialysis of activated preparations first against Tris-saline pH 7.3 then against Tris-saline containing 0.001 M edetic acid (EDTA) led to removal of the added ions and to continued high activity indicating a removal of a pressor inhibitor rather than direct activation by the heavy metals. Dialysis of a fresh kidney homogenate supernatant against 0.001M cadmium chloride for five days and subsequent extraction of the resultant precipitate and diffusate with 2: 1 chloroform-methanol led to no diminution of pressor activity when the extracted material was added to separate samples of unactivated homogenate supernatant. The latter finding suggested that the postulated inhibitor is either made strongly unavailable for reuse or is degraded on removal.